Alan Rossner, David P Wick, Ryan F LeBouf, Christopher Lutes, Marley Carroll
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引用次数: 0
Abstract
Ideally, measuring exposures to volatile organic compounds should allow for modifying sampling duration without loss in sensitivity. Traditional sorbent-based sampling can vary sampling duration, but sensitivity may be affected when capturing shorter tasks. Diaphragm and capillary flow controllers allow for a range of flow rates and sampling durations for air sampling with evacuated canisters. The goal of this study was to evaluate the extent to which commercialized capillary flow controllers satisfy the bias (±10%) and accuracy (±25%) criteria for air sampling methods as established by the National Institute for Occupational Safety and Health (NIOSH) using the framework of ASTM D6246 Standard Practice for Evaluating the Performance of Diffusive Samplers to compare their performance with diaphragm flow controllers in a long-term field study. Phase 1 consisted of a series of laboratory tests to evaluate capillary flow controller flow rates with respect to variations in temperature (-15-24 °C). The results demonstrated a slight increase in flow rate with lower temperatures. In Phase 2, the capillary flow controller was evaluated utilizing a matrix of parameters, including time-weighted average concentration, peak concentration (50-100× base concentration), air velocity across the sampler inlet (0.41-0.5 m/s), relative humidity (20-80%), and temperature (10-32 °C). Comparison of challenge concentrations with reference concentrations revealed the aggregate bias and overall accuracy for four tested compounds to be within the range of criteria for both NIOSH and ASTM standards. Additionally, capillary flow controllers displayed lower variability in flow rate and measured concentration (RSD: 2.4% and 4.3%, respectively) when compared with diaphragm flow controllers (RSD: 6.9% and 7.2%, respectively) for 24-hr laboratory tests. Phase 3 involved further testing of flow rate variability for both diaphragm and capillary flow controllers in a field study. The capillary flow controller displayed a lower level of variability (RSD: 5.2%) than the diaphragm flow controller (RSD: 8.0%) with respect to flow rate, while allowing for longer durations of sampling.
期刊介绍:
The Journal of Occupational and Environmental Hygiene ( JOEH ) is a joint publication of the American Industrial Hygiene Association (AIHA®) and ACGIH®. The JOEH is a peer-reviewed journal devoted to enhancing the knowledge and practice of occupational and environmental hygiene and safety by widely disseminating research articles and applied studies of the highest quality.
The JOEH provides a written medium for the communication of ideas, methods, processes, and research in core and emerging areas of occupational and environmental hygiene. Core domains include, but are not limited to: exposure assessment, control strategies, ergonomics, and risk analysis. Emerging domains include, but are not limited to: sensor technology, emergency preparedness and response, changing workforce, and management and analysis of "big" data.